text
stringlengths 0
234
|
|---|
these system calls are linux-specific.
|
.sh notes
|
suppose the following scenario for
|
.br clock_realtime
|
or
|
.br clock_realtime_alarm
|
timer that was created with
|
.br timerfd_create ():
|
.ip (a) 4
|
the timer has been started
|
.rb ( timerfd_settime ())
|
with the
|
.br tfd_timer_abstime
|
and
|
.br tfd_timer_cancel_on_set
|
flags;
|
.ip (b)
|
a discontinuous change (e.g.,
|
.br settimeofday (2))
|
is subsequently made to the
|
.br clock_realtime
|
clock; and
|
.ip (c)
|
the caller once more calls
|
.br timerfd_settime ()
|
to rearm the timer (without first doing a
|
.br read (2)
|
on the file descriptor).
|
.pp
|
in this case the following occurs:
|
.ip \(bu 2
|
the
|
.br timerfd_settime ()
|
returns \-1 with
|
.i errno
|
set to
|
.br ecanceled .
|
(this enables the caller to know that the previous timer was affected
|
by a discontinuous change to the clock.)
|
.ip \(bu
|
the timer
|
.i "is successfully rearmed"
|
with the settings provided in the second
|
.br timerfd_settime ()
|
call.
|
(this was probably an implementation accident, but won't be fixed now,
|
in case there are applications that depend on this behaviour.)
|
.sh bugs
|
currently,
|
.\" 2.6.29
|
.br timerfd_create ()
|
supports fewer types of clock ids than
|
.br timer_create (2).
|
.sh examples
|
the following program creates a timer and then monitors its progress.
|
the program accepts up to three command-line arguments.
|
the first argument specifies the number of seconds for
|
the initial expiration of the timer.
|
the second argument specifies the interval for the timer, in seconds.
|
the third argument specifies the number of times the program should
|
allow the timer to expire before terminating.
|
the second and third command-line arguments are optional.
|
.pp
|
the following shell session demonstrates the use of the program:
|
.pp
|
.in +4n
|
.ex
|
.rb "$" " a.out 3 1 100"
|
0.000: timer started
|
3.000: read: 1; total=1
|
4.000: read: 1; total=2
|
.br "\(haz " " # type control\-z to suspend the program"
|
[1]+ stopped ./timerfd3_demo 3 1 100
|
.rb "$ " "fg" " # resume execution after a few seconds"
|
a.out 3 1 100
|
9.660: read: 5; total=7
|
10.000: read: 1; total=8
|
11.000: read: 1; total=9
|
.br "\(hac " " # type control\-c to suspend the program"
|
.ee
|
.in
|
.ss program source
|
\&
|
.ex
|
.\" the commented out code here is what we currently need until
|
.\" the required stuff is in glibc
|
.\"
|
.\"
|
.\"/* link with \-lrt */
|
.\"#define _gnu_source
|
.\"#include <sys/syscall.h>
|
.\"#include <unistd.h>
|
.\"#include <time.h>
|
.\"#if defined(__i386__)
|
.\"#define __nr_timerfd_create 322
|
.\"#define __nr_timerfd_settime 325
|
.\"#define __nr_timerfd_gettime 326
|
.\"#endif
|
.\"
|
.\"static int
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.